Sludge Management: An Exploratory Research Report in Bangladesh

The treatment and disposal of industrial and residential sludge is an environmentally sensitive problem. Some traditional disposal routes, such as disposal at sea, are coming under pressure which necessitates finding alternatives. This book describes the effect of composted sludge on the growth of Acacia auriculiformis and Swietenia mahagoni seedlings in the nursery. The experiment was established and analyzed at the nursery of the Institute of Forestry and Environmental sciences, University of Chittagong, Bangladesh with a view to find out a suitable substitute of forest top soil for raising quality seedlings by using composted sludge incorporation with soil. The seedlings were evaluated in seven different treatments (including the control) for three months. Field germination, nodulation status, and physical growth parameters of seedlings namely; shoot height, root length, collar diameter, fresh and dry weight of shoot, root and nodule were recorded after one, two and three months of seed sown and chemical parameters of every treatment such as pH, organic carbon, nitrogen, phosphorus, potassium, chromium, nickel, manganese, cadmium and zinc were analyzed before and after the experiment. Field germination percentage of A. auriculiformis and S. mahagoni seeds were highest in treatment T5 and T6 respectively. Among the sludge amended soil, treatment T5 for A. auriculiformis and treatment T3 for S. mahagoni showed better performance of shoot and root growth compared to other treatments. The highest collar diameter was observed in the combination of soil and residential sludge (1:1) for both the species. The highest number of nodule was recorded from soil amended with residential sludge (2:1) and highest fresh and dry weight of nodule also found from the same combination. Shoot and root fresh weight of A. auriculiformis was highest in combination of soil and residential sludge in the ratio of (2:1). But for S. mahagoni highest shoot fresh weight was in treatment T3 and root fresh weight was in treatment T2, moreover, highest shoot and root dry weight was found in the same combination. Percentage of organic carbon and nutrients (nitrogen, phosphorus and potassium) content were highest in soil amended with residential sludge (1:1) both before and after the experiment over A. auriculiformis and S. mahagoni seedlings. From the study, it can be recommended that soil amended with residential sludge (2:1) on A. auriculiformis and soil amended with industrial sludge (3:1) on S. mahagoni provided better performance compared to other treatments.